Aircraft may include one or more hydraulic systems to actuate various devices, including the brakes. Typically, in the event of a failure of one or more of the hydraulic systems, hydraulic brake accumulators provide limited hydraulic pressure to the brakes. The accumulators act as energy storage devices by maintaining hydraulic pressure. However, once the stored energy, i.e., pressure, is used, it is not available again until the accumulator is recharged.
Thus, upon landing of the aircraft after a hydraulic failure, any cycling of the brakes uses up some of the stored pressure in the accumulator until the pressure drops below a useful level. Depending upon pilot braking technique or the function of an autobraking and/or anti-skid system, the stored pressure in the accumulator can be depleted very rapidly resulting in little or no brake function after initial brake application. The accumulators could be increased in size/capacity to account for these variations. However, doing so adds undesired weight and volume to the aircraft.
Furthermore, the published aircraft takeoff or landing performance may be artificially degraded to account for variations in braking performance. This results in longer takeoff and landing distances or reduced payload.
As such, it is desirable to provide a braking system that does not require hydraulic brake accumulators. In addition, other desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.